1. Field of the Invention
The present invention relates to a method for manufacturing an electronic device using boron nitrides, specifically a method wherein impurities are implanted in a boron nitride layer by ion implantation and the boron nitride layer is then subjected to laser annealing.
2. Description of the Prior Art
Since research relating to electronic devices using boron nitrides is in its early stages, many potential applications of boron nitrides to transistors and integrated circuits are expected. The first step has been developed in applications for diodes, and the applications of diodes have been related to devices emitting blue visible light or ultraviolet rays.
Research into fabricating light emitting devices or other types of electronic devices using boron nitrides has already been disclosed by Mr. Osamu Mishima, for example, in "New Diamonds" Vol. 4, No. 3, Pages 21 to 25. However, there was no disclosure of a method for producing the light emitting device using boron nitrides involving addition of impurities by ion implantation and subjection of the boron nitrides to laser annealing. There was also no disclosure of a method for annealing the boron nitrides by a pulsed laser beam.
In addition, research into the location and temperature relating to the implantation of the impurities in the boron nitrides under precise control has been completely lacking. Ion implantation is believed to be particularly effective in adding impurities into boron nitrides, but because these boron nitrides are synthesized in a non-equilibrium state, it is known that simply using ion implantation with subsequent heat annealing only, as in the case of a silicon semiconductor, is not effective. Also, when heat annealing is performed under a vacuum at 1400 degrees Centigrade, the lattice defects resulting from ion implantation cannot perfectly be eliminated since this heat annealing is an equilibrium annealing.
For this reason, it was impossible to control valence electrons in boron nitrides suitably in the same way as in a silicon semiconductor.
In the case of a silicon semiconductor, after the silicon semiconductor is ion implanted, it is annealed simply by heating to convert to the single crystal, so that in the activation of the impurities (conversion to donor or acceptor) which occurs at the same time, the silicon is melted in the equilibrium system, and the transfer of elements such as silicon in the long range order occurs for recrystallization.
Because the optical energy band gap of a boron nitride is 6.4 eV or greater, the boron nitride transmits a light emitted from a halogen lamp or the like which has an optical energy band gap of the 1 to 1.5 eV range. In this case the boron nitride is annealed in an equilibrium state by the halogen lamp or the like and the annealing is not enough.